Pneumatic tool.



H. LEINBWEBER.

Y PNBUMATIG TOOL.

Y l l APPLICATION FILED 938,774.

JAN. 17, 1907. BENEWED FEB. 23,1909'.

- Patented Nov. 2, 1909.

IWW

HERMAN-LEINEWEBER, OF CHICAGO, ILLINOIS.

. PNEUMATIC ,'rooL.

Specication of Letters Patent.

Patented Nov'. 2, 1909.

Application led January 17, 1907, Serial No. 352,670. Renewed February 23, 1909. Serial No. 479,540.

To all whom it may concern:

Be 1t known that l, HERMAN LEiNEwEBER,

a. citizen of the United States, residing at chambers between which the piston works in the casing.

My object is to provide a novel construction of means for overcoming the tendency in the piston, when the tool is laid aside, or its o eration is interrupted, to attain the dead-point in the casing, which renders the starting of its opera-tion more or less diilicult. This tendency is due to leakage along the piston between it and the barrel of air-pressure until it becomes equalized in both end-chambers, causing the piston to seek the midway position or dead-point between them.

l have especially devised my present improvement for use in the construction of pneumatic tool shown and described in United States Letters Patent No. 778,319, granted to me on the 27th day of December, 1904, and therefore illustrate it in that connection in the accompanying drawing, in which- Figure 1 is a view, mainly in longitudinal sectional elevation, of the'pneumatic tool of the aforesaid patent, rovided with my improvement in its preti;

with my improvement in a modified form and shown partly by a dotted representation, and Fig. 3, a broken longitudinal section of the barrel with the piston in elevation within it and showing my improvement in anwhich contains in its opposite end the larger` air-chamber 9. A supply-passage 10 for the actuating compressed air leads in the handle,

wherein it is valve-controlled as in the afore- Said patent, or otherwise, to a series of rred form; F ig. 2, a .longitudinal section ofthe piston provided ports, one of' which is represented at 11 eX- .tending transversely through the casing and opening linto branches of the passage 10, one of which branches is shown 'at .12, extending lengthwise in the casing-wall and terminating at an annular enlargement forming a pressure-feeding chamber 13 in the casing between the end -chambers therein. EX- haust-ports are provided at 14vand 15. The piston 16, confined in the casing to reciprocate between a hollow cushioning boss 17 in the chamber`9 and the tool-stem 7 in the chamber 8, is closed at both ends and contains a desired number one or more) of longitudinal ducts 18, each terminating at its opposite ends, respectively, in lateral openings 19 and 20 in the iston vnear its ends. These chiots are bored 1n the piston preferably from its rear en'd, where they are closed by plugs 21.

The operation of the device constructed as described is the same as explained in my aforesaid patent ;V that is to say: with 'the parts in the relative-positions in which they are represented in Fig. 1, pressing the thumblever 22, admits air-pressure through the/ passage 10, ports 11 and branches 12 into the feeding chamber 1,3, whence it enters lthe piston-openings 20 and passes through the ducts 18, discharging therefrom at the openings 19 into the chamber 9, wherein it acts against the respective end of the piston to drive the latter against the tool-stem 7.

At the end of this forward stroke of the piston the openings 19 register with the chamber 13, and the air in the chamber 9 escapes through the exhaust-port 15. p With the piston-openings 19 so registering wlth the feeding-chamber 13, pressure .enters those openings to pass through the pistonducts into the chamber '8, therein to act against the forward end of the piston and produce its backstroke, in making which 1t uncovers the exhaust-ports 14 permltting. escape through them of the pressure in the chamber 8.

As shown in Fig. .1 a relatively fine groove, or needle-groove l, 25 is formed lengthwise in the outer surface of the piston to extend to itsirear end from near the plane ofthe openings 20. Should the piston occupy the central dead-point position referredto, it must, to be operated', be preparatorily actuated to the end of its stroke since then,

ing-chamber 13 to either chamberS- or 9 is shut off by the piston. By providing the needle-groove 25, with the piston at the aforesaid dead-point, when air-pressure for starting the operation-is admitted into the feeding-chamber, with which the groove then registers, the latter will soon conduct from the chamber 13suicient air-pressure into the chamber 9 to dislodge the piston from that central position by forcing it to the end of its forward stroke, after which.- it Will be reciprocated regularly in the manner described of its normal operation.

In Fig. 2 the groove 25, which is shown by a dotted representation, terminates short g said. last-named chamber with said intermeof the rear end of the piston at a transverse needle-bore 26 therein leading preferably to its longitudinal center Where it meets the inner end of a needle-hole 27 bored centrally into the piston from its rear end to open into the chamber 9, for starting the piston 'from the dead-point in the manner' described. The needle-like passage may, furthermore, be provided, as represented ,in Fig. 3, `by forming a groove 251, like the groove 25 in the inner Wall of the casing instead of in the piston, to extend from the feeding-chamber 13 to the rear power-chamber 9. With any of the described forms ofr piston-starting pressure-feed passage the result in overcoming the dead-point of the pistonis produced in the same manner.; and the same may, ob-

viously, be embodied in still other forms, With the needle-like passage leading length- Wise of the piston, whether Ain the latter or in the casing-wall, for feeding from a supply chamber 13 air pressure for initially starting the piston to overcome its deadpoint, which is the gist of my invention.

What I claim as new and desire to secure by Letters Patent 'sl l 1. In a pneumatic tool, thecombination of a handle-equipped casing carrying the tool and provided `with an air-pressure in let, end-chambers and an intermediate feeding-chamber for the air-pressure in the, casing, said feeding-chamber communicating with said inlet, a piston reciprocably confined in the casing, having a duet terminating at its ends in lateralopenings in the piston to register with said feeding-chamber, and a needle-like passage extending lengthwise Aof the piston, with one end communieating with an end-chamber, and connecting ing, said feeding-chamber communicating.`

with said inlet,y a piston reciprocablyconfined in the casing, having a duct terminating at its ends in lateral openings in the piston to `register with said feeding-chamber, and al needle-like passage extending Y lengthwise of thepiston, with one end leading tothe rear end-chamber, and connecting diate chamber, for the purpose set forth.

In a' pneumatic tool, the combination of aliandle-cquipped casing carrying the tool and provided withhan air-pressure inlet, end-chambers and-an intermediate feeding-chamber for the air-pressure in the casvpiston lengthwise thereof and extending from a point between its 1ends to its rear end,

for the purpose set forth. 4. In a pneumatic tool, the combination of a handle-equipped casing carrying they tool and provided with an'air-pressure 1nlet, end-chambers andan intermediate feeding-chamber for the air-pressure in the casing, said lfeeding-chamber communicating with said inlet, a pist-on reciprocably oonfined in the casing, havin a duct terminating at its ends in latera openings in the piston to register with said feeding-chamber,` and a. needle-like passage consistin of a groove Iin the piston-surface exten ing from near its forward end, a transverse bore in the piston with which the rear end of said groove connects,- and a bore extending in the piston from its rear end to the inner end of said transverse bore, for the purpose set forth.

HERMAN LEINEWEBER.

In presence of-'- J. R. SPENCE, C. W. WAsHUnN. 

